2.76/2.760 Multiscale Systems Design & Manufacturing · 2.76/2.760 Multiscale Systems Design &...
Transcript of 2.76/2.760 Multiscale Systems Design & Manufacturing · 2.76/2.760 Multiscale Systems Design &...
Sang-Gook Kim, MIT
2.76/2.760 Multiscale Systems Design & Manufacturing
Fall 2004
Carbon Nanotubes
Sang-Gook Kim, MIT
Moore’s Law
Year of introduction Transistors
4004 1971 2,250
8008 1972 2,500
8080 1974 5,000
8086 1978 29,000
286 1982 120,000
386™ 1985 275,000
486™ DX 1989 1,180,000
Pentium® 1993 3,100,000
Pentium II 1997 7,500,000
Pentium III 1999 24,000,000
Pentium 4 2000 42,000,000
The number of transistors per chip doubles every 18 months. – Moore’s Law
_ Moor’s Second Law
Sang-Gook Kim, MIT
Lithography Tool Cost
Year
Expo
sure
tool
pric
e
1980
Historical tool prices
300-mm 193-nm &
157-nm tools
$0
$5,000,000
$10,000,000
$15,000,000
$20,000,000
$25,000,000
$30,000,000
1985 1990 1995 2000 2005
{{
Figure by MIT OCW. After International Sematech.
Sang-Gook Kim, MIT
Aerial density, hard disk
• Superparamagnetic Effect“a point where the data bearing particles are so small that random atomic level vibrations present in all materials at room temperature can cause the bits to spontaneously flip their magnetic orientation, effectively erasing the recorded data. “
Graph removed for copyright reasons.
Sang-Gook Kim, MIT
Limit of Optical Lithography• W = k λ/NA (Rayleigh Eqn.) = λ/(2. n.NA )• In 1975, 405 nm (Hg H-line) at an NA of 0.32, a linewidth of 1 µm • deep-UV (248-nm), 193 nm, 157nm
Table 1: Wavelength "Generations"Intel Road Map
Year Node Lithography1981 2000nm i/g-line Steppers1984 1500nm i/g-line Steppers1987 1000nm i/g-line Steppers1990 800nm i/g-line Steppers1993 500nm i/g-line Steppers1995 350nm i-line -> DUV1997 250nm DUV1999 180nm DUV2001 130nm DUV2003 90nm 193nm2005 65nm 193nm -> 157nm2007 45nm 157nm -> EUV2009 32nm and below EUV
193 nm immersionlithography
NanoimprintingSoft LithographyDip Pen LithographySPM-based patterning
Sang-Gook Kim, MIT
Nanotechnology
Science meets Engineering
Top-down Method
- nanostructures by shrinking macrostructures
Bottom-up Method
- self assembly of atoms or molecules into nanostructures
Nanomanufacturing
Sang-Gook Kim, MIT
Carbon nanotube• 1959: Richard Feynman’s famed talk.• 1981: Binnig and Rohrer created the STM to image individual atoms.• 1985: Curl, Kroto, Smalley discovered C60.• 1993: Iijima, Bethune discovered single wall carbon nanotubes.• 1998: Cees Dekker’s group created a TUBEFET
• Discovered by Sumio Ijima (NEC) in his study of arc-discharge products. Nature, 354, 56 (1991)
• Giant Fullerene molecules made of sheets of carbon atoms, coaxially arranged in a cylindrical shape.– • SWNT, single-walled nanotube (1 < d < 3 nm.)– • MWNT, multi-walled nanotube (d > 3 nm)
Sang-Gook Kim, MIT
Properties of Carbon Nanotubes
• Size: dimensions of ~1 nm diameter (~20 atoms around the cylinder)
• Electronic Properties: Can be either metallic or semiconducting depending on the diameter or orientation of the hexagons
• Mechanical: Very high strength and modulus. Good properties on compression and extension
• Highest Young’s Modulus of all known materials (Y ~ 1.2 TPa).• Extraordinary mechanical resilience: compression, tension, torsion
and buckling without breaking C-C bonds
Graphene sheet
Roll up Chirality
*Graphene is a single planar sheet of sp2 bonded carbon.
Diagrams removed for copyright reasons.
Diagrams removed for copyright reasons.
Sang-Gook Kim, MIT
Rolling up graphene layer
0θ = °
0 30θ< < °
30θ = °armchair
zigzag
chiral
Nanotubes
1.P. J. F. Harris, Carbon nanotubes and related structures: new materials for the twenty-first century, (Cambridge University Press, Cambridge, UK, 1999).
21 amanCh +=
223 mnmnad cctube ++=
π
[ ])2/(3tan 1 mnm += −θ
Diagrams removed for copyright reasons. See source below.
Sang-Gook Kim, MIT
Possible Chiral Vectors21 amanCh +=
223 mnmnaCh cc ++=
M. S. Dresselhaus, Electronic Structure of Chiral Graphene Tubules, Appl. Phys. Lett. 60 (18), 1992
metal semiconductor
(n-m) = 3q metallic(n-m) = 3q ±1 semiconducting
223 mnmnad cctube ++=
πDiagram removed for copyright reasons.
Sang-Gook Kim, MIT
Characterization
• Structural• Electrical• Optical
Sang-Gook Kim, MIT
Vibrational modes in nanotubes
Diagrams removed for copyright reasons.
Sang-Gook Kim, MIT
LightTransmitted
Absorbed
Scattered
…IR
…RamanWhat will happen?
Raman Spectroscopy
nanotubes
Graph of Raman Intensity vs. Frequency removed for copyright reasons.
Sang-Gook Kim, MIT
• Non-destructive, contactless measurement– Room Temperature– In Air at Ambient Pressure– Quick (1min), Accurate in Energy
• Diameter Selective (Resonant Raman Effect)• Diameter and Chirality dependent phonons
– Characterization of (n,m)– Related to Low Dimensional Physics
Raman SpectroscopyRaman Spectroscopyof Carbon Nanotubesof Carbon Nanotubes
M. S. M. S. DresselhausDresselhaus and P. C. and P. C. EklundEklund,,Advances in Physics 49 705 (2000)Advances in Physics 49 705 (2000)
Sang-Gook Kim, MIT
Synthesis• Arc discharge
– Nanotubes found in soot produced in arc-discharge with catalytic metals such as Fe, Ni and Co (S. Iijima, 1991)
• Laser ablation– YAG laser ablation of graphite target in a furnace at 1200
°C. (R. Smalley, 1996)The location and alignment of the synthesized nanotubes can not be controlled.
• CVD– NT grown from nucleation sites of a catalyst in carbon
based gas environments (Ethylene, Methane, etc.) at elevated temperatures (600 - 1000 °C).
Control of location, alignment, length and diameter, spacing between tubes
Sang-Gook Kim, MIT
Arc Discharge Laser Ablation
5-20mm diameter carbon rod Nd-Yb-Al-garnet Laser, 1200
Y. Saito et al.Phys. Rev. 48 1907 (1993)
A. Thess et al.Science 273 483 (1996)
• Yields >70% SWNT if double pulsed
• Ropes 10-20 nm dia, 100 µm length
• How to scale up?
Diagram removed for copyright reasons.
Diagram removed for copyright reasons.
Sang-Gook Kim, MIT
Chemical vapour deposition (CVD)
• Acetylene over iron nanoparticles 700OC forms MWNT covered with amorphous C on outer layer
• Ethylene, hydrogen + methane over Co, Ni, Fe nanoparticlesat 1000OC forms 70-80% SWNT uncapped
• 2CO -> C + CO2also forms NT
Diagram removed for copyright reasons.
Sang-Gook Kim, MIT
VLS Mechanism
<111>siliconcrystal
silicon substrate
vapor
Au-Sialloy(meltedparticle)
Si nanowire
Process diagram removed for copyright reasons.
Porous Anodic Alumina FilmsPorous Anodic Alumina Films
Anodization Reaction :
2Al + 3H2O →Al2O3 + 6e- +6 H+
Experiment Setup :
A
Al film Pt film Water or Ice bath
V
Electrolyte
* Al film is electrochemically polished before anodization
• Controlling parameters:– Voltage, Electrolyte, Temperature,
Time• Cell size D ~ 2.5 × V (nm) • Pore size d ~ V (nm) • Pore size can be enlarged in acids
D
d
Side Top
Courtesy of Prof. M. Dresselhaus, MIT. Used with permission.
Alumina Templates on Silicon Wafers
Si (100)
patterned conducting layer
thermal evaporation
Si (100)
patterned conducting layer
electrochemical
Si (100)
patterned conducting layer
Al
polishing
anodization
Si (100)
Si (100)
deposition
porous alumina
nanowires
Al
selective etch patterning
Si (100)
M. Dresselhaus, MIT
Sang-Gook Kim, MIT
Nanowire by Alumina TemplateOblique View Cross Section
The new Al2O3/Si structure conserves the dense uniform porous morphology with long channels, but consists of a thinner barrier layer.
Filled
Sang-Gook Kim, MIT
Block Copolymer TemplateBlock Copolymer Template
PS+PMMA copolymers
PMMA<10%
PMMA<30%
PMMA50%
Diagram removed for copyright reasons.
Sang-Gook Kim, MIT
Filling methodsFilling methods
• Electrochemical deposition
electrode
electrolyte
• Chemical vapor deposition
• Pressure injection of melt
• Vapor condensation
COLD
HOT
• Sol-Gel
Courtesy of Prof. M. Dresselhaus, MIT. Used with permission.
Sang-Gook Kim, MIT
Vertical growth with controlled density
• Aligned growth through PECVD• Control nanotube density through controlling catalyst site density
Photos removed for copyright reasons.
Sang-Gook KimZ. Ren, BC
Aligned Carbon NanotubeGrowth
Catalytic CVD process: thermal or PE CVD
Carbon Source Gas
Dilution Gas
C2H2: relatively low temp.CH4: high temp.
NH3, N2, H2
Thermal Decompositionon Catalysts (Co, Ni, Fe)
finite solubility with carbon
NH3
c c c c c
NH3C2H2
Plasma ionized
Thermal Pyrolysis
Carbon Nanotube growth
Sang-Gook Kim, MIT
MIT CNT PECVD
Electrode(steel) G
Electrode Connector I(steel) E
Electrode Connector II(steel) F
Support for electrodeand thermocouple
(steel) D
Sang-Gook Kim, MIT
Vertically grown CNTs
• Growth modes
• PECVD parametersDiameterLength
Sang-Gook Kim, MIT
The Debye Length• At some distance from the perturbing charge the electric
potential energy will be equal to the thermal (kinetic) energy• The quantity
is called the (electron) Debye length of the plasma
• The Debye length is a measure of the effective shielding length beyond which the electron motions are shielding charge density fluctuations in the plasma
02
BDe
e
k Tnqελ =
Sang-Gook Kim, MIT
Carbon-nano tube Growth using MethaneGrowth Conditions:
• Growth Time: 25 minutes
• Methane flow rate: 200sccm; Ammonia flow rate: 100sccm
• Pressure: 8 Torr
• Temperature: 600 C
• Plasma Voltage: 500V; Power: 165-215 Watts
Results:
• Length of tubes: 1-1.5 micro meters
• Diameter of tubes: 100-150 nm
• Perpendicularity: Vertical (Straight)
Sang-Gook Kim, MIT
CNTs with methane PECVD
Sang-Gook Kim, MIT
Kazuhiko et al. APL, 78, 539, 2001
SWCN directly grown on silicon tip
Wide usage:high resolution imagingchemical biological sensor
Fabrication:manual assembly(mounting)CVD growth
Photos removed for copyright reasons.
Sang-Gook Kim, MIT
Nanotube AFM tipY. Nakayama et al, J. Vac. Sci. Tech., B18 (2000) 661.
• Merits of NT AFM tip– High aspect ratio– Small diameter– Flexible– Conductive
DNA Double helix
Photos and diagram removed for copyright reasons.
Sang-Gook Kim, MIT
Challenges for Carbon Nanotube Research
• Process control to produce nanotubes with same diameter and chirality
metallic or semiconducting
• Develop large-scale, high productivity synthesis methods
• Develop large-scale, long range order assembly processes
Sang-Gook Kim, MIT
Nanowire Array (Charles Lieber)
How to make horizontal wiring networks?
Source: Prof. Charles Lieber, Harvard University.
Image removed due to copyright reasons.
Sang-Gook Kim, MIT
Directed Assembly
• One-dimensional assembly into functional networks– Lieber group, Science (291,
2001)
Figures removed for copyright reasons.
Sang-Gook Kim, MIT
Aligned NT• Large arrays of well-
aligned Carbon on glass– Ren, Science (282,
1999), SUNY
Photos removed for copyright reasons.
Sang-Gook Kim, MIT
Nanotubes for manufacturing
• Growing and controlling nanotube is a coupled process.
• Decoupling them as we do sodding?
Seeding
Sodding
Sang-Gook Kim, MIT
Carbon Nanotube Assembly
Vertically grown MWNTsRen, J. Mater. Res.16 ( 2001)
Nanostructures by growing only?
Photos removed for copyright reasons.
Sang-Gook Kim
Fluidic Self-assembly
Nanopellets
Nanopellets
Guided Assembly
Sang-Gook KimS. Kim, US patent application No 60/417,959
Nanopelleting
Si Trenches Ni catalyst CNTs growing Filling trenches
Planarization
Release
@BC @BC
Transfer to receptor
Remove filler
M-bond
XeF2
O2 Plasma
Sang-Gook Kim, MIT
1) RIE patterning
Si substrate
2) Deposition seed layerCarbon nano tube growing
Seed layer
Si substrate
Carbon nano tube
SOG
Seed layerSi substrate
Carbon nano tube
4) CMP
SOG
Seed layerSi substrate
Carbon nano tube5) Pelletizing
3) SOG deposition/Dry/Cure
SOG
Seed layer
Si substrate
Carbon nano tube
Sang-Gook Kim, MIT
Bundle CNT nanopelletCMPed and Transplanted
Ni(MTL,15nm)/SiO2/Si
After CMP and then O2 ashing
Sang-Gook Kim, MIT
Pelletizing & Transplanting
After XeF2 etching
Sang-Gook Kim, MIT
High aspect ratio nanopellets
1-2 microns
Nanocandles
Single strand
Cold cathode array,FED, Data storage, Multi-E-beam array for NGL
bundle
Sang-Gook Kim, MIT
Oxygen plasma etchingof polyimide layer
Apply SU-8
New Nanopelleting process
Apply polyimide
Pattern SU-8
XeF2 etching
Transplant
Single strand MWNT vertical growth
Sang-Gook Kim, MIT
Processing Result
• High-aspect-ratio nanocandles with 20 µm in diameter and 110 µm in height achieved
• Single strand CNTs under progress
Material: SU-8 2075
Sang-Gook Kim, MIT
Micro probe tip
Nanocandle
In-Plane Assembly of High-Aspect Ratio Nanocandle
• Mechanical in-plane assembly of nanocandle in the V-groove with a micro probe tip
• Bonding of nanocandle in the V-groove with a drop of epoxy
CNT
SU-8
SEM of the assembly
Sang-Gook Kim, MIT
MIT Nanopipette
• Nanotube assembly to the tip of a micropipette
Nanopellet
micropipette
SCNT
• Nanotube assembly to the tip of an in-plane AFM
- Parallel Imaging and Pipetting
- Multi-energy probing- Manufacturable- Arrayable
Sang-Gook Kim, MIT
Potential applications
• Massive Parallel Nanoprobe Array • Nanojet Printing• Nanotip Cell Manipulation• 3D CNT structures